Differential gear

ABSTRACT

A lockable differential gear has one integral differential gear housing ( 1 ) which contains apertures ( 8 ) opposite to each other by way of which the inner parts of the differential gear can be mounted.

The invention relates to differential gears of the type more preciselydefined in the preamble of claim 1.

When using common differential gears, so-called self-lockingdifferentials, are used in order to prevent the one-sided spinning ofdrive gears.

The German laid-open application 20 38 137 discloses a self-lockingdifferential gear in which one bolt is supported in one first part of adifferential gear housing and is axially secured with a pin and thedifferential bevel gears are rotatably supported upon the bolt. Thedifferential bevel gears are in operative connection with the axle bevelgears which are connected via brakes with the differential gear housing.The differential gear housing comprises two parts; one main part and onecover, which is screwed with the main part. This is necessary to makemounting the parts in the differential gear housing possible through thelarge circular axial aperture and carrying out treatments of thedifferential gear housing. By screwing the first differential housingpart to the second differential housing part, the differential gearbecomes more expensive and the total weight and needed diameter of thedifferential gear are increased.

DE 38 41 234 C2 likewise discloses a lockable differential gear havingfirst and second differential gear housing parts interconnected viascrew threads. Since the screw threads are situated radially outside thebrake, the differential gear radially needs more installation space.

The problem on which this invention is based is to provide a lockabledifferential gear which stands out by small radial dimensions of thedifferential gear housing thus being more economical and lighter.

The problem is solved by a differential gear according to the preambleof the main claim and having the features thereof.

The differential gear has one integral housing, according to theinvention, the wall of which has at least one aperture through which theaxle bevel gears, differential gears and the brakes can be mounted.Through the aperture, lubricant reaches into the differential gearadditionally cooling the brake. The edges of the aperture are preferablyprovided with a radius designed so that stresses be reduced in thedifferential gear housing during operation of the differential gear.

In another embodiment, the differential gear housing has great wallthickness in the area of the edge of the aperture.

In one other development of the invention two apertures which areopposite to each other are situated in the differential gear housing.The differential gear housing has one bolt on which are supported twodifferential bevel gears and which supports itself in holes of thedifferential gear housing. The bolt is held in the differential gearhousing via one pin. The differential gear housing has a wall area ofgreat thickness in the area where the bolt is held in the differentialgear housing. The great thickness of the edge of the aperture and thegreat thickness in the area of the hole for the bolt are designed sothat a fitting is possible along the axis of rotation of thedifferential gear. By the differential gear housing being designed inone piece, it needs considerably less radial installation space whichalso makes itself noticeable by less weight and lower cost. The axlebevel gears have a toothing upon which are held internal discs of themulti-disc brake, the external discs of the multi-disc brake beingconnected with the differential gear housing via a toothing orsemicircular shackles. The toothing drifting force on the axle bevelgears is used for applying a locking torque via the multi-disc brake. Inone other development of the invention a spring element can additionallyact upon the multi-disc brake and produce a basic locking torque.

Other features can be deduced from the description of the Figures whichshow:

FIG. 1 is a section through the axis of rotation and through the bolt ofthe differential gear;

FIG. 2 is a spatial graph of the differential gear;

FIG. 3 is a section through the central axis of the bolt forming a rightangle with the axis of rotation of the differential gear; and

FIG. 4 is a section through the axis of rotation of the differentialgear forming a right angle with the central axis of the bolt.

FIG. 1:

A differential gear housing 1 is designed in one piece and has on eachof its axial ends cylindrical extensions 2 by way of which thedifferential gear is rotatably supported around its axis of rotation.One bolt 3 is held in the differential gear housing 1 via one pin 4.Differential bevel gears 5 are rotatably supported upon the bolt 3. Axlebevel gears 6 are connected via engaging gears with the discs of onebrake 7, the outer discs of the brake 7 supporting themselves in thedifferential gear housing 1. One spring element 14 additionally actsupon the multi-disc brake thereby producing a basic locking torque. Thespring element 14 can be designed here as a plate spring or also ascorrugated spring, the spring element being located in one recess orgroove of the differential gear housing so that the prestress of thespring element is adjusted via the depth of the recess or of the grooveand the spring element is in the linear area of its characteristic linewhereby the adjustment of the basic locking torque is simplified.

FIG. 2:

The differential gear housing 1 has apertures 8 opposite to each otherthrough which the differential bevel gears and the axle bevel gears, thesame as the brakes, can be mounted in the differential gear housing. Theaperture 8 is dimensioned so that even if the parts can be mounted inthe differential gear housing 1, the necessary torque still is nottransmissible. For the purpose, the edge area of the aperture 8 isprovided with a radius 9 whereby the stresses are reduced. In addition,the wall of the differential gear housing 10 is made thicker in the areaof the edge of the aperture 8. The wall 11 is, likewise, made thicker inthe area in which the bolt 3 is held in the differential gear housing 1.In the axial area, where the differential gear 1 can be fastened with acrown gear, ribs 12 are disposed in order to increase the stabilitywithout this negatively affecting the weight. Since the differentialgear housing 1 is designed in one piece, it is possible to reduce theinner radius of a crown gear since a stop 13, likewise, has a smallradius.

FIG. 3:

For reasons of clarity the housing is shown exclusively in section andthe inner parts removed. The two apertures 8 opposite to each other,have reinforced walls 10 in their edge area. In the area of fastening ofthe bolt 3 in the differential gear housing 1, the wall 11 is likewisemade reinforced.

FIG. 4:

The apertures 8 of the differential gear housing 1 make is possible tomount the inner parts and conduct the needed treatments.

REFERENCE NUMERALS

-   1 differential gear housing-   2 cylindrical extensions-   3 bolt-   4 pin-   5 differential bevel gears-   6 axle bevel gears-   7 brake-   8 aperture-   9 radius-   10 wall-   11 wall-   12 ribs-   13 stop-   14 spring element

1-14. (canceled)
 15. A differential gear having one housing (1) whereaxle bevel gears (6) are in operative connection with differential bevelgears (5), the housing (1) being rotatably supported around an axis ofrotation and a support resulting via cylindrical extensions (2) of thedifferential gear housing (1), the at least one axle bevel gear (6) isconnectable via one brake (7) with the differential gear housing (1) andthe differential bevel gears (5) are supported in the differential gearhousing (1) via at least one bolt (3), the differential gear housing (1)is designed in one piece and has between the cylindrical extensions (2)at least one aperture (8) by way of which the differential bevel gears(5) and axle bevel gears (6) and the brake are mounted and by way ofwhich lubricant reaches the brake.
 16. The differential gear accordingto claim 15, wherein the brake (7) is designed as multi-disc brake. 17.The differential gear according to claim 15, wherein the brake (7) isprestressed via one spring element (14) so as to obtain a basic lockingtorque.
 18. The differential gear according to claim 17, wherein thespring element (14) is designed as plate spring or corrugated spring.19. The differential gear according to claim 17, wherein the springelement (14) is located in one of one recess or one groove of thedifferential gear housing (1).
 20. The differential gear according toclaim 19, wherein the prestressing of the spring element (14) isadjustable via one of a depth of the recess or of the groove.
 21. Thedifferential gear according to claim 19, wherein the spring element (14)in its prestressing is disposed so that the spring element (14) is in alinear area of a spring characteristic line during operation of thedifferential gear.
 22. The differential gear according to claim 15,wherein each axle bevel gear (6) is connected with the brake (7). 23.The differential gear according to claim 15, wherein two differentialbevel gears (5) are supported in the differential gear housing (1) viathe one bolt (3).
 24. The differential gear according to claim 15,wherein the differential gear housing (1), one wall (11) of greatthickness has in an area of connection with the bolt (3).
 25. Thedifferential gear according to claim 15, wherein two apertures (8) aresituated in the differential gear housing (1) opposite to each other.26. The differential gear according to claim 15, wherein edges of theaperture (8) have a radius (9) which reduces stresses in thedifferential gear housing (1).
 27. The differential gear according toclaim 15, wherein a size of the aperture (8) is determined by parts tobe mounted.
 28. The differential gear according to claim 15, wherein thedifferential gear housing (1) has walls (10) of great thickness in aarea of an edge of the aperture (8).